I am new to surface drives, and recently bought a used JB Mud Motor with a 15 HP Lifan, 9 x 7 prop, and roughly a 1:1 ratio (odd?). The top sprocket is a 32 tooth and I believe the bottom is a 31. It was pushing my 1548 about 14 MPH with just me, and 8-10 MPH with a hunting load and a buddy. It bogged the 15 HP pretty bad, and I had some issues with the motor, so I replaced it with a stock Predator 22HP. The 9x7 cavitates with the new 22 HP so I have ordered a new 11x10 as suggested by Hill Marine. I haven't been able to get the boat up on plane and get any speed out of it, so that is the goal.

My question is this:

Will I likely need to gear down from the 1:1 in order to run this new prop in the proper RPM range with the new 22hp? If so, any suggestions on a ratio to start with?

Thanks in advance for any advice.

Seems like a big prop for that motor, but you can start with a 1.5:1 gear ratio is what I would do. Then go from there.
If you don't have a tach, you better get one!
That will help you figure if gearing needs to be changed

11x10 is the correct size for the motor, but I'm not sure about the gearing.

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Old MB Hyper 18 HP came with a 32 top and 50 tooth lower and it could turn a 11x10 MB prop. That gearing ought to be pretty close for your application.

Thanks guys.

So I got the new prop installed, and the motor will pull it just fine. I can run about 20 MPH. I don't have a fixed tach to see what I am turning while running down the river, but with checking it with my auto multi meter, It turns 3800 rpm on the trailer with no load. I have a tach ordered.

So here's my new question.....

Does anyone know how to sucessfullly remove/bypass/cheat the governor on a new 22 hp Predator?

I was able to achieve 4000 rpm (no load) by putting a stiffer spring on the throttle linkage. That gave me another 4 MPH BUT.....the boat would only run 100 yards and then bog and shut off. Idled rough too. moved the spring back and it runs fine at 20 mph.

Any ideas?

Thanks guys.

So I got the new prop installed, and the motor will pull it just fine. I can run about 20 MPH. I don't have a fixed tach to see what I am turning while running down the river, but with checking it with my auto multi meter, It turns 3800 rpm on the trailer with no load. I have a tach ordered.

So here's my new question.....

Does anyone know how to successfully remove/bypass/cheat the governor on a new 22 hp Predator?

I was able to achieve 4000 rpm (no load) by putting a stiffer spring on the throttle linkage. That gave me another 4 MPH BUT.....the boat would only run 100 yards and then bog and shut off. Idled rough too. I put the original spring back and it runs fine at 20 mph. I am not trying to abuse the motor and push it too hard, but I thought I would turn it up just a bit as the current 3800 rpm seems a bit low, and from the sound of it, I believe she could handle a tad more.

Any ideas?

I ordered my 04 hyper 23hp with a 36/52 pulley set and was able to spin a 12x12 from Hopkins with no problem. It had headwork, cam, rockers and a few other go fast items tho.

The issue is with the fuel pump you will have to go to low pressure electric and your motor will pull fine at 4000rpms. I had same issues with mine google pred fuel issues and you will find a few of the same problems others have had.



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